Skin fastener



Jan. 25, 1944. P. F. ROSSMANN 2,339,381

' SKIN FASTENER Original Filed Dec. 19, 1941 INVENTOR. Ail efer m lioaamafln 44/ fZa ATTORNEY Patented Jan. 25, 1944.

SKIN FASTENER Peter F. Rossmann, Snyder, N. I, assignor to- Irving Rossi, West Orange, N. J.

Original application December 19, 1941, Serial No. 423,565. Divided and this application January 6, 1942, Serial No. 425,716

12 Claims. (cuss-) This application is a division of my co-pending application Serial No. 423,565, filed December 19, 1941, entitled "Skin fastener.

The present invention relates to a clamping device or skin fastener and a method of making the same and which serves for temporarily assembling or clamping together perforated sheet material; in particular metal sheets or plates preparatory to and to facilitate a rivetingoperaclamping forces especially as required for riveting operations substantially without damage to the metal sheets.

A further object is the provision of a simplified clamping device constructed in such a manner as to enable quick and instant insertion through the perforations in the sheets to be assembled or clamped even in the hands of an unskilled or "untrained operator.

tion or any other work to be carried out on said Anoth r O j t is to Provide a fastener which material. A 4 while small in size will permit of applying conl my copendingapplication, Serial No.-384,46 1,- siderable clamping pressure between a pair of filed March'21, 194'1, entitled Clamping device, perforated sheets capable of withstan in the I have described a device of this character com-' forces exerted thereon during a riv Other prising essentially a body member or support 1 p r tion. provided with an opening preferably equal to the Still anotherobject is the provision of aclampperforations in the sheets or. other material to ns device of the above t pe ul s y be clamped, a clamping element arranged i adapted for removing the burr on the edge of movable relation to said support and having the perforations of the sheetsbeing clamped, or pair of resilient legs or prongs provided with in other words, to provide a combined clamp and shoulders and biased into engagement with each reamer for use n p o d materialother, and a spreader arranged in relatively fixed The above and further objects and advantages relation to said support and projecting through of y invention will become more app from said opening. Normally the spreader is interthe following detailed description taken with refposed between said prongs to hold the same in erence to the accompa y ng drawin fo n spaced apart position against their natural bias part f th Specification and wherein! I with the combined cross-sectional area of said Figure 1 Vertical cross-Sectional View prongs and interposed spreader being substana skin fastener constructed in accordance with tiallg equal to and filling said opening. Furth rthe principles of the invention; Figure 2 is a more. I provide suitable spring means interposed cross-section taken on line 2-2 of Figure 1; Figbetween said spreader and clamping element t ure 3 is. a partial view of the improved clamping I permit of movement of said clamping el t element embodied in Figure 1; Figure 4 is a. between two extreme positions, one of said posi- Perspective partial e showing the p aderv tions resulting in the ends of said prongs a d embodied in Figure 1; Figure 5 is a vertical said shoulders passing beyond said spreader a d view showing a fastener constructed and used on being operated into engagement with ea h other skin sheets in about twice natural size inthe in such a manner as to enable the insertion off inserting p s ti n du n the op ratin y a said prongs through the aligned perforation of Figure 6 is a perspective view showing the novel a pair of sheets or any other piece to be clamped, locking element for holding the parts of the clam and the other of said positions resulting in clamp- 40 in the assembled position. i ing engagement and firm locking of said sheets Like reference characters identify like-parts "in. or piece between said support and shoulders held the difierent views of the drawing. in spaced apart position by said spreader, In the drawing, the numeral l0 indicates the An object of the present invention is the prob y e r 0 pp t Of my improved fastener vision of various features of improvement emwhich, in the xample sh wn. h e Shape Of bodied in a device of the above general character a cu t p ovided with a fla e "at t p both in order to simplify the construction and t end and having a bottom l2 curved or outwardly improve the operation thereof. vaulted as shown in l3. Bottom I2 is provided A specific object is to provide a simplified skin Y with a central opening or perforation I which fastener, the component parts of which are re-! is preferably equal in diameter to the aligned duced a minimum and which c be q y holes or perforations in a pair of super-posed and easily assembled and disassembled during sheets A and B, or any other piece to .be clamped manufacture andfor the exchange of broken or \or assembled. d f ct P S- I y The clamping-element l5 which is shown sep- Another object is to permit the use of heavy arateLv in'Figure 3 is consguted, according tq the improved method and construction by a unitary wire member of semi-circular or segmental crosssection as shown in Figure 2, bent into a U-shape with the fiat surfaces facing each other to form a pair of resilient legs 01' prongs. The latter are shaped as shown in Figure3 to comprise a first pair of substantially parallel sections l6 and I6 adjacent to their bent portion, followed by intermediate sections l1 and I1, being at first bent inwardly at a small angle (15) to the central or symmetry line and then outwardly at a slight angle (about 3), the lowermost or outer sections l8 and I8 provided with shoulders or protuberances 20 and 20' being in tum substantially parallel for a distance at least equal to the crosspiece 22 plus the thickness of the member I at its perforation ll plus the thickness of the plates forming impressions in the sheets or other piece being clamped or' assembled. Although shown curved substantially throughout its area, it is A and B. These parallel portions l8 and I8 are urged or biased into engagement with each other in the normal position as shown in Figure 3.

The parallel outer prong sections l8 and I8' are passed through the opening II in the hottom l2 and are held in spaced apart position both in the inefiective or non-use and in the operative position by 'a substantially T-shaped member comprising a; spreader 2| (see Figure 4) and a cross-piece 22 interposed between said prongs in sliding engagement with the flat inner faces thereof as shown in Figure -1. The under-surface 23 of the spreader portion or cross-, piece 22 is suitably curved to substantially conform to the inside of the bottom l2 with which it cooperates in maintaining the spreader 2| in a predetermined position relative to the cup or body member ID.

The upper end of the clamping member I5 projects beyond the cup l0 and has secured thereto a head or cap 25 by the aid of a crosspin 28 passed through diametrical perforations in the cap and embracing the bent outer portion of the prongs. Pin 26 is.held in position by a slit resilient ring-shaped locking element 21 placed in a circumferential groove of the cap 25 to enable an easy assembly and disassembly of the device during manufacture and for the quick exchange of broken or defective parts during use, as will be described in greater detail hereafter. of resilient steel wire and slit as shown in Figure 6 with the ends biased away from each other to allow of sufficient separation for-insertion in-the grooves of cap 25. and locking therein in a manner well understood A coil spring 3|! encircling the prongs of element I5 has its upper end engaging theupper surface of the spreader portion 22, the upper end of the spring resting within the recess .formed by an angular flange 3| in the undersurface of and engaging the cap 25. Spring 3|] is desig ed to provide sumcient clamping forceto firmly lock the shoulders 20 and 20' against t e un- The locking ring 21 is preferablyto be understood that only the outer edges of the bottom I2 need be curved for the purpose mentioned, thereby obtaining at the same time a desired area for,the distribution of the force exerted by. the spring 30 and consequently a'desired predetermined clamping pressure between sheets A and B.

The clamping element l5 may be produced from a piece of spring steel wire of proper length cut from a suitable supply. According to one practical method, the wire is at first converted from its normal round shape into a flattened and bent shape by means of a suitable pressing operation preferably in two or more steps; Thus, forexample, the round straight wire is flattened in a first operation to assume a semi-circular or segmental cross-section and the shoulders 20 and 20 are formed in the same or a subsequent pressing operation by using a suitable die. Then the wire still in a straight position is bent in another die to provide the intermediate sections l1 and I1, whereupon the ation with the sections l8 and I8 and shoulders 20 and 20' engaging each other in the manner shown-in Figure 3. In this shape the element is then suitably tempered to provide the necessary springiness or resiliency.

An advantage of a clamp or skin fastener described hereinbefore is the fact that none of, the

component parts thereof are connected permanently, thus enabling an easy and quick assembly during manufacture and disassembly to exchange damaged or defective components.

The assembly of the clamp is as follows: To begin with, the spreader 2|22 is placed between the lower parts of the prong sections l1 and ll of the element l5, the spreader 2| readily fitting between the prongs. and with the cross piece-22 projecting equally from the opposite sides from the prongs. This sub-assembly is then inserted into the cup In heldin a suitable support or mounting jig, the shoulders 20 and 20' readily passingthrough the opening I,

dersurface of sheet 3 in the operative position of the fastener as shown in Figure 1, or against the undersurface of the bottom |2 in the ordinary or non-use condition of the device. To this end, for a clamping device of the size here illustrated forclamping sheets, thespring emp oyed is such that it requires thirty-five pounds to separate the sheets. p

The vaulted or curved construction l3 of the bottom H of the cap, or body member ID enables the employment of a comparatively very heavy Spring to secure an adequate clamping or firm locking of the sheets A and B by the fastener without the danger of damageto same as by until-the cross piece 22 engages the inner surface of the bottom i2. The spring 30 is then placed around the prongs. pressed position the spring will extend beyond the upper ends of the prongs. The spring is then compressed by the aid of a suitable tool until the upper end -'of element |5 sufilciently projects beyond the upper end of the spring, whereupon cap 25 is placed over the prongs and locked in position by passing cross-pin 26 through theholes in the cap and between the prongs, whereby upon subsequent release of the spring the prongs will be'drawn in an upward direction. consequentlysections l8 and I8 will slide-over the faces ofthe spreader 2| thus being. spread apart. This upward movement is continued until the shoulders 20 and 20' engage the undersurface of thebottom |2 of cup ID. The locking ring 2| is applied to the cap before or after release of the spring 30. The. disassembly of the clamp may be effected in a similar mannen by first removing locking ring 21 and then pin 26, thus permitting the removal of spring 30. Element I5 is then pushed in a downward direction until sections l8 and I8 have passed beyond the spreader 2| and are operated intn engagement so as to'allow withdrawal of In this uncomaasassi 3 the prongs in a manner understood from the foregoing.

As pointed out' hereinafter, the curved or arched shape of the bottom l2 prevents scratchin addition has the further effect of concentrating sufficient pressure around the circumference of the perforation in the sheet. When the clamp is used for temporarily holding sheets to be rivseparating when the rivets are applied to adjacent perforations or during any other work performed on the sheets. unnecessarily heavy spring and a large clamp requiring a strong tool such as a plier for insertion into and removal from the perforations in the sheets. By the improvement proposed according to the present invention, due to the concentration of the pressure upon a small area around the perforation, both the size of the spring and the entire clamp as well as of the operating tool are reduced to a minimum and 'the operation itself greatly simplified and expedited. Thus, it was found by practical experiments that when the fastener is used to hold alignment of the clamp in the holes in its final position, thereby further simplifying and facili-- tating the insertion and operation thereof:

- While I have shown the support or body member III in the form of a, cup it will be understood that the same may take any other suitable shape such as a U-shaped metal strip or angle piece or the like sufficient to form a housing support for the device, such modifications and variations of the parts of the device being readily obvious to those skilled in the art.

In use, the cap 25 is pressed against the cup III by compressing spring 30 with the aid of a suitable tool such as a'toggle device or a plier engaging the outer surface of the cap on the one hand and the undersurface of the flange II on the other hand if heavyspring pressures are required such as in clamping sheets for performing a riveting or similar operation. In this (inserting) position the prong sections l8 and I8 are'passed beyond the spreader 2| and operated towards each other by their own spring action. The maximum diameter of the prongs and shoulders, 20 and-20' when biased towards each 'otherpermits of readyinsertion through the perforations in the sheets A and B as illustrated in Figure fishowing the position at the start of the insertion cycle. The shoulders 20 and 20 are designed in such a manner as to provide 5 when in engagement with each other aready slip fit in the'perforations', and, due'tothe par'alleb shape of the lower prong sections I8 and [8" it a is clearly seen thatthe insertion isgreatly simplified by providing a ready guidance for the prongs through the perforations during the inserting operation. Moreover, the parallel arrangement of the lower prong sections l8 and I8 not only insures a ready guidance of the clamp during the insertion into the holes of the ing and scarring of the upper skin surface A and v 5 sheets to be clamped, thereby substantially dispensing with the necessity of employing a trained orskilled operator, but it furthermore prevents any lateral movement or play of the prongs during the insertion cycle'which is not the case in. lo prior constructions wherein the ends of the prongs form an angle and wherein substantially the shoulders only are biased into engagement with each other during the inserting operation. In this position the spreader 2| which substantially conforms to the inner faces of the prong This might lead to an sections I! and I1 will be readily positioned between the latter, resulting in the prong sectionsv l8 and lB'fremaining in parallel position and properly aligned and,preventing lateral movement or canting as pointed out above.

At the end of the insertion cycle, that is when the curved bottom [2 engages the upper surface of the sheet A'as shown in Figure 1,- the spreader 2| will be so positioned with respect to the sheets A and B as to cause the prong sections 3 and I8 and the shoulders 20 and 20' to become spread apart by moving in an upward direction towards the sheets A .and B of body member l0 upon release of the spring .311 so as to result in a firm looking or clamping of the sheets between the shoulders 20 and and the'bottom l2 in the manner understood from the foregoing and shown in Figure 1.

In order to remove the fastener from the sheets or any other piece upon completion of a riveting or other operation, the spring 30 is again compressed by pressing the cap 20 by the aid of a plier or the like against the cup I q in the same manner as described above, thereby again oper- 40 'ating the prong sections I8 and 3' into engage-.

ment with each other and enabling a withdrawal "of the prongs from the perforations. After the clamp has been withdrawn the spring pressure is released thus returning it to its normal or nonif use position as is readily understood.

It will be evident from the foregoing that the invention is not limited to the specific details of construction and arrangement of parts shown and disclosed herein for illustration but that the underlying novel principles are susceptible of variations and modifications coming within the broader scope of the invention as defined in appended claims. The specification and drawing are accordingly to be used in an illustrative rather than alimiting sense.

1. In a. device forclamping perforated sheets in superposed relation, a-body having an opening, asubstantially U-shaped resilient clamping prong of substantially uniform cross-section throughout slidable through said opening and having its outer leg portionsprovided with shoulders and biased toward each otherv normally under their own spring tension, a spreader resting against said body and positioned between said legs for maintaining said leg portions in normally spaced relation and forming therewith a crosssectional area of a diameter equal to the diameter of the perforations of the sheets to be in the longitudinal direction of said prong, spring means arranged to have one end engaging the inner end of said prong and having its opposite end bearing upon said spreader for maintaining said prong in a predetermined normal position with respect to said body and for maintaining said spreader against longitudinal movement with respect to said body in the direction of said prong, said legs when moved beyond said spreader upon movement of said prong relative to said body against the action of said spring means bein operated towards each other to permit ready insertion of said legs and shoulders into the perforations of the eets tobe clamped, and said legs on being rel sed moving under the action of said spring means to their normal position with respect to said body and spreader at which said legs are in spaced parallel-position, whereby to clamp said sheets between said shoulders and said body.

2. In a device for clamping perforated sheets in superposed relation, a body having an opening, a substantially U-shaped clamping prong slidable within said opening and formed from a single elongated metal member of equal segmental cross-section throughout with the legs of the U having their flat surfaces in face-to-face relation, the outer leg portions of said prong being provided with shoulders and biased towards each other normally under their own spring tension, a spreader resting against said body and positioned between said legs for maintaining said leg portions in normally spaced relation and forming therewith a cross-sectional area of a diameter equal to the diameter of the perforations of the sheets to be clamped, said outer leg portions being ofi-set towards each other to form when in engagement due to the resiliency ofsaid prong a combined uniform cross-section for a distance at least equal to the total thickness of the sheets to be clamped, said spreader and said body taken in the longitudinal direction of said prong, spring means arranged to have one end engaging the inner end of said prong and having its opposite end bearing upon said spreader for maintaining saidprong in a predetermined normal position with respect to said body and for maintaining. said spreader against longitudinal movement with resp ct to said body in the direction of said prong, said leg portions when moved beyond said spreader upon movement of said prong relative to said body against said spring means being operated towards each other to permit ready insertion of said legs and shoulders into the perforation of the sheets to be clamped, and said legs on being released moving under the action of said spring means to their normal position with respect to said body and spreader at which said le s are in spaced parallel position, whereby to clamp said sheets between said bodyand said shoulders.

3. In a device for clamping perforated sheets in superposed relation, a body having an opening, a'substantially U-shaped clamping prong slidable through said opening and having its outer leg portions provided with shoulders and normally biased towards each other under their own spring tension, a spreader resting against said body and positioned between said legs for maintaining said leg portions in normally spaced relation and forming therewith a cross-sectional area of a diameter equal to the diameter of the perforations of the sheets to be clamped, said leg portions forming when in substantial engagement a combined uniform cross-section for a distance at least equal to the total thickness of the sheets to be having one end engaging the inner end of said I prong and having its other end engaging said spreader for maintaining said prong in a prededetermined normal position with respect to said body and for maintaining said spreader against longitudinal movement with respect to said body in the direction of said prong, said legs when moved beyond said spreader upon movement of said prong relative to said body against said spring being operated towards each other to permit ready insertionpf said legs and shoulders into the perforations of the sheets to be clamped, and said legs on being released moving under the action of said spring to their normal position with respect to said body and spreader at which said legs are in spaced parallel position, whereby to clamp said sheets between said shoulders and said body.

4. In a device for clamping perforated sheets in superposed relation, a body having an opening, a substantially U-shaped retainer slidable through said opening and having a pair of resilient legs provided with shoulders at their outer ends and biased toward each other under their own spring tension, a spreader resting against the inside of said body and having a portion projecting through said opening and positioned between the outer portions of said legs for maintaining said legs in normally-spaced relation and forming therewith a cross-sectional area of a diameter equal to the diameter of the perforations of the sheets to be clamped, said outer leg portions forming when in substantial engagement'a combined uniform cross-section for a distance at least equal to the total thickness of the sheets to be clamped, said spreader and said body taken in the longitudinal direction of said retainer, .spring means interposed between the inner end of said retainer and said spreader to urge said retainer into a predetermined normal position with respect to said body and to maintain said spreader against longitudinal movement with respect to said body in the direction of said legs, said legs, when moved upon movement of said retainer relative to said body against said spring means beyond said spreader, being operated toward each other to reduce their combined diameter to permit ready insertion of said legs and shoulders into the perforations of the sheets to be clamped, said legs on being released moving under the action of said spring means to their normal position with respect to said body andspreader, whereby to clamp said sheets between said shoulders and the outside of said body, a cap encasing the inner end of said retainer and adapted to receive said spring means, and locking means for locking said retainer and cap comprising a pin passed through said cap and between the bend of said legs.

5; In a device for clamping perforated sheets in superposed relation, a body having an opening, a substantially U-shaped retainer slidable through said opening and having a pair of re silient legs provided with shoulders at their outer ends and biased to engage each other under their own spring tension, a spreader resting against said body and having a portion projecting through said .opening and positioned between said legs for maintaining the. outer portions of said legs in normally spaced relation'and forming therewith a cross-sectional area of a diame terequal to the diameter of the perforations of tions and a pair of outer shoulders and biased towards each other, a

the sheets to be clamped, said outer leg portions forming when in engagement a combined sub- ,stantially uniform cross-section for a distance at least equal to the'total thickness of the sheets to be clamped, said spreader and said body taken in the longitudinal direction of said. retainer,

spring means interposed between the inner end of said retainer and said spreader for maintaining said legs in a .predetermined normal position with respect to said body and for maintaining said spreader against longitudinal movement relative to said body in the direction of said legs, said legs when moved beyond said spreader upon through said opening and constituted by a unimovement of said retainer relative to said body against said spring means engaging each other to permit ready insertion of said legs and shoulders into the perforations of the sheets to be clamped, said legs moving on being released.

by said spring means under the action of said spring means to their normal position with respect to said body and spreader ,at which said legs are in spaced parallel position, whereby to clamp said sheets between said shoulders and said body, a cap encasing the inner bent portion of said retainerand adapted to receive said spring means, and a locking member for securing said cap to said retainer comprising a pin passed through said cap and between the inner surface of the bend of said'legs, and'a circumferential slit wire engaging a groove in said cap for locking said pin.

6. A'clam ping device comprising a body having an opening, a retainer slidable through said tary wire member bent in' U-fashion to provide a pair of resilient prongs, said prongs having a pair of parallel sections adjacent torthe bend thereof, a pair of inwardly bent intermediate sections, and-'a pair of outer parallel sections having shoulders and biased towards each other, a spreader in fixed relation to said body and interposed between said prongs, a cap secured to the bent end or said prongs, and spring means interposed between said body and said cap for causing clamping action between said I body and said shoulders.

9. In a clamp for clamping sheets through perforations therethrough, a body member having an opening, a clamping element projecting through said opening be'mg constituted by a unitary wire member bent in U-i'ashion to provide a'pair of resilient prongs, said prongs having a first pair of parallel sections ad acent to the bend thereof, a pair of inwardly bent intermediate sections, and -a pair of parallel outer sections having shoulder-s and biased towards each other, a spreader infixed opening and having a pair of resilient legs biased towards each other under their own spring ten; sion and having their outer ends provided with shoulders, a spreader in fixed relation to said body and positioned between said legs for maintaining the outer portions of said legs in nor-.

mally spaced relation and forming therewith -a cross-sectional area of a diameter. equal to the diameter of the perforations of the sheets to be clamped, the outer portions of said legs sliding through said opening and being off-set towards each other to form when in engagement due to their inherent resiliency a combined uniform cross-section for a distance of the order at least equal to the total thickness of the sheets to be relation to said body and interposed between said prongs, a cap, a removable cross pin passed through diametrical periorations in said cap and embraced by the bent end portion of said prongs, means for locking said pin in position and spring means interposed between said body and said cap clamped, said spreader and said body taken in v the longitudinal direction of said retainer, spring means interposed between the inner end of said I shoulders and biased toward each retainer and said body for urging said retainer into a normal retracted position with respect to legs' areat a spaced parallel position, whereby said bodyfsaid legs when moved beyond said for causing clamping action between and said shoulders.

10. In a clamp for clamping sheets through perforations therethrough, a body member hav-- ing van opening,'a clamping element projecting through said opening and constituted by a unitary wire member bent in U-fashion to provide a pair of resilient prongs, said prongs having a first pair Of parallel sections adjacent to the bend thereof, a pair of inwardly bent intermediate sections,and a pair of outer parallel sections having other, a spreader in fixed relation to said body and interposed betvveen saidprongs, a caphaving a circumferentidl groove a' removable cross pin inserte'd in diametrical perforations of said cap and said body a slit ring in said groove for locking said pin and spring means interposed between said body and to'clamp said work between=said shoulders and said body.

'7. In a clamp for clamping sheets through perforationstherethrough, a body member having an opening, a clamping element projecting through said opening and-constituted by a unitary wire member bent in'U-fashion-to provide a pair of resilient prongs, said prongs having a first pair of parallel sections adjacent to the bend thereof, a pair of inwardly bent intermediate secsaid cap for causing clamping action between said body and said shoulders.

11. In a clamp for clamping sheets vthrough perforations therethrough, a body member hav-.

ing-an opening, a clamping element projecting through said opening and constituted by a unitary wire member bent in a U-fashion to provide a pair of resilient prongs having shoulders at the ends thereof and biased towards each other,- a"

spreader in fixed relation to said body and interposed between said prongs, a cap, a removable cross pin inserted in diametrical perforations of.

said cap and embraced by the bent portion of said prongs, locking means for said pin, and

parallel sections having spring means interposed between said bod and said cap Ior causing clamping action y between said 12; In a clamp for clamping sheets. through perforations therethrough, a body member haw-- ing an opening, a clamping element projecting through said opening and constituted by a imitary wire member bent in U-iashion to provide a pair of resilient prongs having shoulders at the ends thereof and biased towards each other, a

spreader in flxedrelation to said body and interposed between said prongs, a cap having a circumierential groove, a, removable cross pin inserted in diametrical orations of said cap, a slit ring in said groove for locking said pin, and

I 5 spring means interposed between said body and said cap for causing clamping action between said shoulders and said body.

PE'I'ER F. ROSSMANN. 

